Automatic control of motor-driven pump speeds



T. B. WHI'TTED.

AUTOMATIC CONTROL OF MOTOR DRIVEN PUMP SPEEDS.

APPLICATION FILED MAR.2, 192].

1,41 1,145; Patented M -28,1922.

U T 3 SHEETS-SHEET I.

T. B WHITTED. AUTOMATLC CONTROL OF MOTOR DRIYEN PUMP SPEEDS.

' APPLICAHON HLED MAR. 2 1921.

1 ,41 1 ,145, Patented Mar. 28, 1922.

3 SHEETS-SHEET 2.

T. B. WHITTED.

AUTOMATIC CONTROL OF MOTOR DRIVEN PUMP SPEEDS. APPLICAHON FILED 11111.2. 1921.

1,41 1,145. Patented 1111-. 28,1922.

3 SHEETSSHEET 3.

W Tlwnzm'p. Wbimd -To all whom it may UNITED STATES PATENT OFFICE.

m8 3m wan-rm, OI (mama-rt. IOB'I'H GABOLIIA.

AU'IOILTIC corner. 0] IO'l'Ol-DBIVII' rm m Specification 0! Letters Intent.

Patented Mar. 28, 1922.

Application fled men 8, 1981. Serial Io. 40,215.

concern: Be it known that I, Tnoms Bran Wm'rrnn, a citizen of the United States,

at Charlotte in the county of Meeklenburg and State of North Carolina, have invented certain new and useful Im rovements in Automatic Control of otor- Driven Pum Speeds; and I do hereby declare thefollbwmg to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it iaplpertains to make and use the same.

e present invention relates to a method of automatic control of speed on one or more motor driven pumps according to liquid levels. This invention has as itsobject the automatic control of the capacity of a motor driven sump pump by means of automatically regulating the speed of an electric motor, and the control of the capacity of one or more motor driven booster pumps by automatically regulating the speed of one or more driving motors, ac cording to variation of liquid level in sump.

It has been produced with a view, and will probably be found most applicable to the removing of overburden and mining of phosphate rock and pebble, although it may be used to advantage in other mining or pumping operations.

Its primary object is to reduce the present cost of mining phosphate rock which is attended with the difiiculties enumerated as follows: I

The deposits of phosphate rock foundin the United States and other countries, vary greatly in formation. Those most advantageously mined in the United States are located in and'near Polk County, Florida, where these deposits are found from one to thirty feet under a layer of soil known as overburden. The deposits vary in depth of from one to thirty feet, and largely con- 'sist of blanket formations covering considthe pit under ressure varying from. 125 to 200 pounds. e motor-driven centrifugal pump is placed as near the pit or sump hole as possible, so that it will have as short a suction as possible. This suction has a valve at the end and flexible joints so that it can be swung around in the sump hole. The discharge of pump is iped over the ground tgatlhe place the ov r urden is to be deliv e The high pressure water gun is located so as to play on the ba'nk of overburden. The overburden is washed into the sump hole, and the pump delivers this mixture through the pipe line to its destination;

The centri gal pump is generally driven by a wound rotor type induction motor direct connected through coupling, this motor having external resistance with drum controller in the rotor or secondary circuit only, the stator or primary being controlled with a switch, "particularly in case the'stator is wound for 2200 volts.

The suction pipeand pump are primed by water furnished from an outside source. The sump hole is filled with water if it is not already fuLLand the suction of the pump submerged. The equipment is now ready to start. The motor driven pump is put into service by closing the primary switch, -in the meanwhile the stream of water from the high pressure gun is turned on the bank of overburden. In case the sump hole, which is approximately a small hole, is full or rising rapidly, the motor-driven pump is brought up to full speed by means of drum controller and resistance, hand 0 rated by the-operator. In case it is found that the motor-driven pump is reducing the amount of material and water in the sump hole, and the level is falling, the motor-driven pump speed is reduced. The speed of the motordriven pump is chan to suit the amount of water and material being washed into the sump hole.' In consequence the speed of motor-driven pump is being changed from timeto time to suit conditions, as the amount of material being washed down and in sump hole varies due to many varying har conditions, such as bank being very has a 50% regulation, controlled by the drum controller and resistance.

It is a very serious matter if the pump is allowed to pump the sump dry, if it does the pump will become dead, losing its priming, thereby causing a shut-down. It is also necessary to pump as fast as the material is washed into the sump hole, con

sequcntly the present method of operation is to have a motor operator stationed continuously at the drum controller, and vary the speed of the motor-driven pump to suit. Furthermore, in case of a shut-down when there is a rich mixture of solids in pipe line, they settle to the bottom of pipe and in some cases the whole pipe line has to be taken apart and the solids removed.

'When the overburden is to be delivered beyond the capacity of one pump, a booster centrifugal pump is connected in series with the pump opposite sump hole, generally at a distance so that the load is divided. The

booster pump is driven by the same type of motor, and has a motor operator stationed to control the speed of this motordriven pump also by means of a drum controller and resistance to suit the conditions of operation. The motor operator of the booster pump must control the speed of his pump to suit. He has in some cases a pressure and vacuum gauge to tell him when to speed up and when to slow down. By listening to material passing through pipe line he can also control his pump, or he the pump housemay be signaled from located at sump hole. He can also tell from his animeter in primary of motor. The correct operation of the booster pump is that it should exactly follow the operation of the pump at sump hole, or there will be a shut-down causing loss of production, etc.

From the above explanation it will be seen that the successful operation of this method of handling material depends largely upon the motor operators controlling their pump or pumpsso that these pumps will handle water and solids as they are delivered to sump hole, but in no case should they permit the sump hole to be pumped dry or below the end of suction ipe, so as to lose the priming and create de ays, shut-downs and loss of production. In consequence the operators are required to continually change the speed of the motor-driven pump or pumps, which varies the output of materials pumped. so that it follows as nearly as possible the amount being delivered to sump hole.

In mining phosphate rock, with or without booster pump, the method is exactly similar to mining of overburden, as explained above. However, sometimes the rock deposit has to be blasted with dynamite to break it up and assist the high pressure water gun in getting out the tonnage. This mixture of phosphate rock, debris and water is pumped to what is known as a washer plant, and the phosphate is separated from the refuse, cleaned and transported to the.

roaster, or elsewhere.

The labor required in connection with this operation consists of from 6 to 12 men per pit, depending upon whether one or more boosters are used. Two of these men operate the gun, one mans duty being, by means of a controller very similar to that used on an ordinarystreet car, to vary the speed of each motor, start and stop same. Two men are kept at the suction of the pump to keep it from getting clogged. One man is used as a helper. It will thus be seen that with one booster seven men'is the minimum that can operate one pit, eight are ordinarily em ployed.

My invention eliminates one of these men where a single sump pump is used; it eliminates two men when there are in operation a sump pump and a booster pump. In case a second booster pump is necessary, it eliminates a third man. This applies to overburden as well as rock mining, as has been explained the methods used are similar.

Operation in Florida is generally on a 2 1-- hour basis, consisting of three shifts. Consequently we save an average of two men on the overburden'operation and two men on the rock mining operation, the total saving therefore would be twelve men per day.

A mining equipment indicates one overburden operation and one mining operation. Some of the mines in this district have as many as five or more complete mining units in service at the same time. This invention therefore will make a large reduction in cost of operation.

In the drawings, wherein like symbols refer to like or corresponding parts through out the several views,

Fig. 1 is a sectional view made through the bank of overburden and phosphate rock and showing in side elevation an apparatus constructed according to the present invention;

Fig. 2 is a plan view thereof; and

Fig.' 3 is a diagrammatic view showing the circuit arrangement.

Referring more particularly to the drawings, 1 designates the bank 012 overburden which lies above the stratum 2 of phosphate rock. In the bank 1 of the overburden an excavation 3 is made providing a pit for the introduction of the hydraulic and pumping apparatus and for providing a space in which the various operations required may be performed by the workmenl At one side of the it and adjacent one bank of the overbur en there is made a sump 23 in which to catch the water and washed-down material resulting from the hydraulic. action.

The hydraulic gun or nozzle is designated at 4 and is supplied with water under suitable pressure from a desired source by means of a hose 5. A centrifugal pump 6 is installed in the pit close to the sump 23 and is directly connected with an electric mo tor 7 by which it is driven.

The suction pipe 8 of the pump 6 extends down to a desired depth in the sump 23 and is adapted to draw the water and suspended material into the pump 6 by which such material is elevated through the discharge pipe 9 to a suitable destination with out the pit 3. If desired, a second pump and motor unit 10 may be provided on the surface above the it and including a booster pump 12 and an e ectric motor 13.

A panel board 14 is mounted in the pit 3 preferably close to the motor 7 and a second panel 15 carrying the solenoid contactors is also mounted in the pit and, with advan tage, close beside the panel board 14. A controller 16 is mounted in the pit above the sump 23 being provided with a shaft 17 carrying arms 18 and 19, to the latter of which is attached a counterbalance weight 20. This arm 19 also receives the end of a flexible cable 21 which passes over the companion arm 18 and carries a float 22 at its lower end which rides upon the surface of the liquid in the sump 23. The arms 18 and 19 preferably diverge upwardly as indicated in fieferring more particularly to the circuit diagram shown in Fig. 3, the invention is shown installed in connection with the usual three-wire alternating current system in which the main line is represented at 24 and is rovided with a main switch 25 preferab y operating under oil. The main circuit 24 is directly connected to the field winding of the motor 7, and, if the booster motor 11 is also employed, a switch 26, also with advantage bem an oil switch, may be closed to put the fielfof this booster also directly in circuit with the main line 24. A transformer 27 is coupled in the main line 24 betweenthe main switch 25 and the motor 7, the secondary of the transformer being connected in a circuit 28, 29. This circuit includes the controller and the solenoids 30 of the solenoid contactors carried by the panel 15. The solenoid contactors are shown in Fig. 3 to be seven in number to correspond with the seven contacts of the controller. I

Lead wires 31, being seven in number, couple the contacts of the controller separately to one end of each of the solenoids 30,

a common return wire 32 being provided,"

which is coupled in multiple to the other ends of the various solenoids 30; this return wire 30 being connected to the branch wire 29 of the secondary circuit. The armature slip rings 33 of the motor 7 are connected in 16 an armature resistance. circuit by wires 34 which are three in number and each of which connects with one end of one of the three resistance elements 35, 36 and 37.

The other ends of these resistance elements are coupled together in common by a wire 38, and a wire 39 connected to the wire 38 extends to a common or bus wire 40 connecting one end of the resistance elementsto one of the contacts of each of the solenoid contactors. The wires 34 connect with the other contacts of the first three solenoid contactors, while additional wires 41 are secured at one end to the remaining other contacts of the solenoid contactors and at their opposite ends are secured to various sections of the resistance elements.

A similar circuit arrangement is made against the bank, and it washes down the overburden or phosphate rock into the sump 23 where the agitation of the water keeps the particles of rock and pebble in suspension. The main line switch 25 is closed and also the booster switch 26, if desired. The motor or motors will thereupon start at their lowest speed assuming that the level of the liquid in the sump is at low ebb. In this position the float 22 will be at its substantially lowest point and consequently the controller 16 will be in such a position that all of the resistance elements will be connected in cir cuit with the armature windings of the motors. This condition will continue until the liquid level rises in the sump 23, which will cause a corresponding rising of the float 22. This will have its reaction upon the controller so that through the solenoid contactors one section of the resistance will be cut out of the motor circuits, thus allowing the motor to proceed at a greater speed and to correspondingly drive its pump whereby to drawa proiportionately greater amount of material an liquid from the sump commensurate to the level.

Should the liquid level in the sump still rise despite this increased action of the pump or pumps, the float 22 will be carried 'upwardly to a further point, which will actuate the controller to cut out a second section of r the resistance, thus permitting the motor-ormotors to operate at a still faster speed. The

pumping operation will in this way be increased until a maximum speed is obtained when all of the resistance is cut out and the motor is operating with a short circuited rotating element or armature at a synchronous speed less the slip. When operating in this or any other position, should the quantity of material washed into the sump begin to subside, the float 22 will act in the reverse man ner, cutting in step by step more resistance and thus decreasing the speed to correspond with the quantity of material to be pumped.

The electric circuits may be extended to one or more boosters, and all may thus be automatically governed by the same controller and float switch. The invention thus provide for the automatic reduction or increase in speed of the pump motors in accordance with the position of the level of the liquid in the sump and in doing so it dispenses with the services of the operator Who is usually detailed to operate the controller. Moreover, the invention, by the use of a secondary circuit 28, 29 which is stepped down to substantially 110 volts through the transformer 27 "from the main circuit 2 which ha usually QQOG'volts, provides a comparatively safe place for the operators to perform their orlr inasmuch as they are not subjected to accidents occurring frequently Where the high voltage of the main line directly used in and about the motors and controller.

lit is obvious that various changes and modifications may he made in the details of construction and design of the above specificaliy described embodiment of this invention without departing 'i'rom the spirit thereof, such changes and modifications being" restricted only by the scope of the following claims.

What is claimed is:

l. The herein described apparatus for antomatically controlling the speed of a motor driven pump for removing the material from the sump, eluding control means for the pump acting to raise and lower its speed in proportion to the amount of material being washed into the sump, substantially as described.

2. The herein described apparatus for automatically controlling the speed of a motor driven pump for removing the material from the sump, including automatic regulating means for the pumping apparatus adapted to cause the latter to be driven at a fast or slow speed according to the position of the liquid level in the sump, substantially as described.

3. The herein described apparatus for automatically controlling the speed of a motor driven pump or removing the material irom a sump, including a motor driven booster pump acting to assist the first mentioned pump, and regulating means for both of said pumps controlled automatically by the level of the fluids in the sump, suhstantially as described.

4. The herein described apparatus for entomatically controlling the speed oi a motor driven centrifugal pump for removing the material from the sump, an electric motor for driving said centrifugal pump, and regulating mean for the motor acting to automaticall increase and decrease the speed of the same in proportion to the quantities of material being delivered to the sump, schstantially as described.

5. The herein described for antomatically controlling the speed of a motor driven centrifugal pump having intake arranged in the sump, control means for said motor including sectional resistance elements, and means for automatically cutting in and out the resistance elements in accordance with the changing level of the liquid in the sump, substantially as described.

The herein described apparatus for tomatically controlling the speed oi a motor driven centrifugal pump adapted to remove the material from the sump, an electric motor coupled to drive said centrifugal pump, and regulating means for the motor including sectional resistance elements, centactors for cutting in and out the resistance elements from the motor, and control means for the contactors, substantially as described.

7. The herein described apparstus tor automatically controlling the speed. a motor driven centrifugal pump having its inlet disposed in the sump, an electric motor coupled to drive said centrifugal pump, governing means for the electric means including a scrtional resistance, and a float device in the sump adapted to rise and fall with the liquid level for controlling the cutting in and out of the resistance elements, substantially as described.

THOMAS Brim Winrrnn.

ltlli 

